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US 756
First Edition
2007-12-19
Reference number
US 756: 2007
© UNBS 2007
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Compliance with this standard does not, of itself confer immunity from legal obligations A Uganda Standard does not purport to include all necessary provisions of a contract. Users are responsible for its correct application |
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© UNBS 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written permission from UNBS. Requests for permission to reproduce this document should be addressed to The Executive Director |
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Tourism, Trade and Industry established under Cap 327, of the Laws of Uganda. UNBS is mandated to co-ordinate the elaboration of standards and is
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical Committee is established to deliberate on standards in a given field or area and consists of representatives of consumers, traders, academicians, manufacturers, government and other stakeholders.
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the general public for comments. The committee reviews the comments before recommending the draft standards for approval and declaration as Uganda Standards by the National Standards Council.
Committee membership
The following organisations were represented on the Chemicals and Environment Standards Technical Committee UNBS/TC 5 in the preparation of this standard:
Urea fertilizer grade — Specification
This Uganda Standard prescribes the requirements and methods of sampling and test for urea fertilizer grade.
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
US 757 Ammonium sulphate nitrate fertilizer — Specification
The fertilizer shall be in the form of a free-flowing crystal powder, granules or prills, free from any visible impurities. The fertilizer may be coated or uncoated.
The fertilizer shall be in the form of crystals, and free from visible impurities. The particle size shall be such that not less than 90 % by weight of the material shall be of particles of size range of 1 mm — 4 mm.
The fertilizer shall also comply with the requirements specified in Table 1, when tested according to the methods prescribed in annexes therein.
| SL No | Characteristic | Type | Method of test | |
|---|---|---|---|---|
| Uncoated | Coated | |||
| (i) | Total nitrogen, percent by mass, min | 45 | 45 – 46 | Annex A of US 757 |
| (ii) | Biuret, percent by mass, max. | 1.5 | 1.5 | Annex A |
| (iii) | Moisture, percent by mass, max | 1.0 | 1.0 | Annex D of US 757 |
| (iv) | Ash content, percent by mass, max | - | 2.5 | Annex B |
The material, when determined by appropriate methods shall comply with the maximum limits specified in Table 2.
| Metal | Maximum limits, mg/kg |
|---|---|
| Arsenic | 20 |
| Cadmium | 7 |
| Mercury | 0.1 |
| Selenium | 1 |
| Lead | 30 |
| Chromium | 500 |
The material shall be packaged in suitable containers in accordance with the Weights and Measures Act.
A certificate of analysis shall accompany each consignment and the following information shall be marked on each packaging container:
Non-corrodible slotted grain probe, of sufficient length to penetrate the whole bag diagonally
2Sampling cup, 2 cm to 2.5 cm in diameter and of length as wide as the stream
Air-tight containers, on which the material has no action
Non-corrodible grain probe, of 130 cm to 155 cm length
Any other suitable apparatus.
For testing compliance of the fertilizer to the requirements of this standard, samples shall be taken from any container or package, or from a number of representative containers or packages, selected at random. The packages or package selected shall be intact and in good external condition. From each of these packages laid horizontally take a full-length diagonal fore using the non-corrodible grain probe. Mix the cores thoroughly to form a representative sample and store in an airtight container.
From each lot or batch take 20 samples (cores) at random, using a non-corrodible grain probe of 130 cm to 155 cm length. Mix the samples thoroughly and store in an air-tight container.
Take 20 samples (cores) at equal intervals through the whole period passage of the lot or batch using the sampling cup described in 5.1.2. Mix the samples thoroughly and store in an airtight container.
Pass the material through a sieve of aperture 1.70 mm. Reduce the material to an amount sufficient for analysis. Sieve through a sieve of aperture 1.0 mm, breaking the lumps. Grind in a mortar the part remaining on the sieve until all the particles run through. Mix thoroughly, transfer immediately to a stoppered wide-mouth bottle and preserve this as the prepared sample for analysis. The grinding and sieving shall be done as rapidly as possible to minimize gain or loss of moisture.
3(normative)
Dissolve 40 g of NaOH in 500 mL H2O, add 50 g potassium sodium tartrate (NaKC4H4O6.4H2O) and dilute to 1 L. Let it stand for a day before use.
Dissolve 15 g CuSO4.5 H2O in carbon dioxide free water (CO2-free H2O) and dilute to 1 L.
To recrystallize, weigh approximately 10 g reagent grade biuret, transfer to 1-litre beaker, add 1 L absolute alcohol, and dissolve. Concentrate by gentle heating to approximately 250 mL. Cool at 5 °C and filter through flitted glass funnel. Repeat crystallization and dry final product for 1 h at 105 °C ± 11 °C in an oven. Remove from oven, place in a desiccator, and cool to room temperature.
Dissolve 1.0000 g recrystallized biuret in CO2-free H2O and dilute to 1 L.
Transfer series of aliquots, 2 mL – 5 mL of standard biuret solution to 100 mL volumetric flasks. Adjust volume to approximately 50 mL with CO2-free H2O add 1 drop methyl red, and neutralize with 0.1N sulphuric acid to pink colour. Add, while swirling, 20 mL alkaline tartrate solution and then 20 mL CuSO4 solution. Dilute to volume, shake for 10 s, and place in a water bath for 15 min at 30 °C ± 5 °C. Also prepare reagent blank. Determine the absorbance A of each solution against blank at 555 nm (instrument with 500 nm – 570 nm filter is also satisfactory) with 2 cm -4 cm cell. Plot standard curve.
Continuously stir approximately 10 g sample containing 30 mg – 125 mg Biuret in 150 mL H at 50 °C for 30 min. Filter and wash into 250 mL volumetric flask, and dilute to volume. Transfer 50 mL aliquot to 100 mL volumetric flask and proceed as in A.2 above.
4(normative)
Weigh accurately about 5 g of the sample into a silica crucible. Ignite the crucible and its contents preferably in a muffle furnace, starting at a low temperature and gradually increasing the temperature to 800 °C. Maintain this temperature for 1 h. Cool in a desiccator and weigh the residue. Repeat until successive weighings do not differ by more than 1 mg.
where,
| m1 | is the mass, in grams, of the residue after ignition; and |
| m2 | is the mass, in grams, of the sample taken for test. |
KS 03-288: 2004, Urea fertilizer grade — Specification
6Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards (UNBS) Certification Mark shown in the figure below.
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made thereunder. This mark can be used only by those licensed under the certification mark scheme operated by the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The presence of this mark on a product or in relation to a product is an assurance that the goods comply with the requirements of that standard under a system of supervision, control and testing in accordance with the certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are continually checked by UNBS for conformity to that standard.
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda National Bureau of Standards.
